The cultivation of aquatic creatures confined in structures such as cages and tanks has long been attractive to those wishing to commercially raise and sell fish, frogs, shrimp, and the like. With respect to certain creatures, such cultivation has proven to be a viable and profitable alternative to standard harvesting practices used in these creatures' natural habitat. With other creatures however, and, particularly frogs, cultivation in an artificial environment has been an inefficient and costly endeavor.
The difficulty of raising frogs in captivity is compounded by the fact that a frog has two distinct stages of life. When a frog egg hatches, a frog begins its first stage of life in a larval form known as a tadpole. In its infancy, the tadpole has a tail and external gills, and lives and breathes exclusively under water. As the tadpole grows, legs develop and the size of its tail and gills begins to decrease. Once the tadpole's lungs are sufficiently developed, it is forced to seek the surface of the water in order to breathe air. At this point in time the tadpole enters a second stage of development into an adult frog. In this stage, the frog spends the majority of its time on dry ground.
These two separate stages of development make raising frogs in captivity difficult for several reasons. First, separate environments must be provided for the tadpoles and the adult frogs. Tadpoles can survive only in water while adult frogs require an environment that is both wet and dry. Second, tadpoles and frogs require different food sources. Additionally, if the adult frogs are not separated from the tadpoles early in their development, the adult frogs will tend to feed on the tadpoles themselves.
Once the frogs are separated from the tadpoles, the adult frogs have to be continually graded and separated by size to avoid the problem of cannibalism. Because the tadpoles, and hence the frogs develop at different rates, the continual grading and separating of frogs is time and labor intensive. The frogs differing significantly in size from other frogs raised in a cultivating enclosure have to be individually captured and then moved to a separate enclosure in which frogs of a similar size are held. Due to the inherent mobility of frogs, this can be a difficult task.
Frogs also become increasingly stressed in the continued presence of man. Excessive human contact with frogs in cultivation can result in disruptive feeding patterns and reproductive cycles among the frogs, which in turn results in smaller frogs and a decreased frog population at harvest time. Moreover, the frogs are susceptible to injury during the grading and separating process. The frogs will inevitably attempt to evade capture, and as a result will often jump into the walls and lids of cultivating enclosures presently being used to raise frogs in captivity.
The above-mentioned inherent characteristics of frogs create competing interests for commercial breeders. The cultivating enclosures need to be small enough to facilitate the rapid capture of frogs during the grading and separating process, and at the same time must be large enough to house a sufficient number of frogs in order to make commercial cultivation economically feasible. In addition, because frogs are susceptible to disease in captivity, the cultivating enclosures should be easily accessible for regular cleaning and at the same time be constructed in such a manner that prevents the frogs from escaping during the cleaning process.
In order to maximize the growth rate and reproduction rate of frogs in captivity, certain climate and light conditions are necessary. Frogs grow at a maximum rate when the surrounding temperature conditions range from approximately 70.degree. to 80.degree. Fahrenheit. A frog's metabolism slows as temperatures fall below 70.degree. Fahrenheit. When temperatures are in a range of 40.degree. to 50.degree. Fahrenheit, the frogs enter a state of hibernation and their growth rate stops. In order to reproduce, frogs generally require approximately 12 hours of daylight and 12 hours of night. Thus, to enable frogs to lay eggs and thus reproduce throughout the entire year, these conditions must be simulated in a controlled environment.
Accordingly, it can be seen that the need exists to provide a method and apparatus for cultivating frogs which maximizes the number of frogs raised to full maturity while minimizing the frogs' exposure to human contact. The need also exists to provide a method and apparatus for cultivating frogs in captivity in a controlled environment while minimizing the labor and costs associated with maintaining the controlled environment.